Overdrive control



Feb- 12, .1952 E. M. cLAYToR OVERDRIVE CONTROL 2 SHEETS-SHEET l Filed Aug. 11, 1949 Feb. 12, 1952 E M. CLAYTOR 2,585,437

OVERDRIVE CONTROL Filed Aug. ll, 1949 2 SHEETS--SHEET 2 e j I y VE-A/ Toe.

el/z 772 MMM,

Patented F eb. 12, 1952 OVERDRIVE CONTROL Edward M. Claytor, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application August 11, 1949, serial No. 109,789

(cl. 19e-4) 9 Claims.

' This invention relates to overdrives used on automotive vehicles whereby, in response to an intermediate vehicle speed, the gearing is automatically changed from low to intermediate speed and whereby, in response to a certain higher vehicle speed, the gearing is changed from intermediate to high speed.

' The object of the invention is to provide a system of electrical control by which the gear ratio changing mechanisms are controlled by electromagnets or solenoids and the operation of a solenoid to effect the change from a higher to a lower ratio of engine speed relative to axle speed is under joint control by a speed responsive switch and a switch which is momentarily closed by release of the accelerator pedal. T o change from a lower to a higher ratio of englne speed relative to axle speed, the solenoid is under control by a manually operated down speed switch and by the opening of an accelerator switch when the accelerator pedal is moved to increase engine power. The system provides for momentarily rendering the engine inoperative to facilitate operation of the mechanisms when shifting from a lower to a higher speed ratio. In this specification, the terms high, medium and low are used in the ordinary sense to mean, respectively, gearing for high vehicle speed, for medium vehicle speed and low vehicle speed.

A further object of the invention is to prevent a. free Wheeling condition when going down hill, or when the brakes are applied. This is accomplished by a switch in the circuit of the down speed switch to prevent shifting from high to medium or from medium to low speeds. This switch is automatically controlled by the brake system when the brakes are applied or can be manually controlled when going down hill and using the engine as the brake.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

- Fig. l is the diagram showing the mechanical connection between an engine shaft and a propeller shaft and a diagram of the electrical control.

Fig. 2 is a view in the direction of arrow 2 of Fig. l.

Fig. 3 is a diagram of a speed responsive switch.

Fig. 4 is a diagram supplementing Fig. 1.

Y Referring to Fig. 1, the shaft-20 is driven by the engine preferably through a clutch (not shown) which automatically closes at an engine speed above idling speed. Shaft 20 is journaled in a bearing 2| and provides a journal 22 for supporting a coupling 44. A sun gear 23 is supported by shaft 20 but is not connected therewith. Gear 23 is connected with a notched disc 24 adapted to receive a. locking pawl 2'5 attached to a pawl rod 26 and guided by bosses 2l (Fig. 2) provided by a part of the gear housing 28. In order that the pawl 25 may be received by a notch of the disc, it is necessary that a notch 29 of a blocker disc 30'be located in alignment with the pawl 25, as shown in Fig. 2. Normally this notch 29 is out of alignment with the pawl 25 because the sun gear 23, when rotating with the shaft 22, moves blocker plate 30 through a frictional connection with the gear 23 so that one of the lugs 3| of the plate 30 will normally engage one of the bosses 2l.

Shaft 20 has an externally splined portion 32 received by internal splines in a disc 33 supporting a plurality of studs 34 on which are journaled planet gears 35 meshing with the sun gear 23 and a ring gear 36 provided by a shell 3l journaled on disc 33 by ball bearings 38. Splined portion 32 is received by internal splines 40 in the inner member 4| of a one-way clutch having rollers 42 through which the member 4| drives the outer clutch member which is provided by shell 31.

Shell 31 is connected with a coupling 44 integral with a shaft 45 connected with a gear 46 meshing with a gear 4l connected with a countershaft 48 whichdrives a gear 49 meshing with a gear 50. Gear 5|)A provides the outer member of a one-way clutch having rollers 5| through which gear 5U drives an inner clutch member 52 integral to or attached to the propeller shaft 53 of the vehicle. Bearings45a, 48a and 53a support shafts 45, 48 and 53 respectively.

Shafts 4:5 and 53 are directly connectible by clutch members 54 and 55, connectible respectively with these shafts. Clutch 54 is connected with shaft 45 by a key 56 engaging a longitudinal groove 5l in this shaft. Engagement of clutch member 54 with 55' is effected by counterclockwise movement of lever 60 pivoted at 6| and having a forked arm B2 carrying studs 63 which engages groove 54 in clutch member 54. Lever 6G is connected with a rod G5. When rod G5 is moved left, clutch member 54 will move into engagement with clutch member 55 and shafts 45 and 54 will be directly connected for medium vehicle speed. The one-way clutch, which includes rollers 5|, permits clutch member 52 to overrun gear 5B.

The shift from medium to high is eiected by causing downward movementl of rod 26 and such torque reversal as will cause the blocker plate 30 to move its notch 29 into alignment with the pawl. When the pawl 25 is received by a notch in the locking disc 24, the sun gear 23, which had been rotating when the transmission was in low and medium, is stopped. Therefore, planet gears 35 are caused to roll around the sun gear 23; and the ring gear 36 provided by the shell 31 is caused to rotate faster than shaft 22. The one-way clutch, which includes rollers 42, permits shell 31 to overrun member 4| connected with shaft 20.

The movements of rods 65 and 2B are controlled by identical solenoids SI and S2, respectively. Each solenoid comprises a base which, as

shown in Fig. 2, is attached to transmission housing 28. Base 1Q (Fig. 1) supports a core 1| surrounded by a main armature attracting coil 12 and an armature holding coil 13. When these coils are energized, an armature 14 is caused to move toward the core Il against the action of a spring 15 confined -between a fixed part 16 of the solenoid and a nut 11 attached to the armature. Spring 15 normally holds the nut against a stop 11a. As nut 11 moves toward the core 1|, it applies force through a spring 18 to the shoulder 19 of a rod which is rod 65 of solenoid SI or rod 26 of solenoid S2. If movement of rod 65 toward the left is arrested by abutting the teeth of clutch members 54 and 55 before they become connected, the spring 18 will be compressed. When there is a momentary reversal of torque transmission in which theV vehicle propeller shaft 53 momentarily becomes the driving member,y the teeth abutment is relieved and the clutch members 54 and 55 engage. This torque reversal is effected by momentarily lifting the foot from the accelerator pedal so that engine power will decrease while the vehicle continues on its own momentum. Similarly, with respect to the solenoid S2 when the motion of pawlv is arrested by the blocker 30, the

spring 18 will be compressed. Release of the accelerator pedal causes reversal of torque transmission such that the blocker plate will turn to bring its notch 29 into alignment with the pawl.

The solenoid windings are conneotible with a current source which is a generator 80 driven by the vehicle engine and connected by a reverse current or cut-out relay 8| and wire 82 with a storage battery 83 which the generator charges .v

when the cut-out relay is closed. As known to those skilled in the art, this relay closes in response to theV attainment of a certain generator voltage. When this voltage. is attained, coil 3b of a relay 3R will be energized and its contacts 3c will close. Relay 3R is provided so that thev overdrive control system cannot be operated unless the generator is functioning properly when the transmission is in low.

If relay contacts 3a are closed at a predetermined medium vehicle speed, a speed responsive or governed switch GSI closes. There is a switch ASl normally closed when the accelerator pedal is released. To shift from low to medium, the driver releases the accelerator pedal so that switch AS closes. Then the following circuits are established: wire 82, resistor 83, switch AS, wire 84, coil 3c of relay 3R which is a hold-in coil which will keep the contacts 3a closed although energization of coil 3b might be insufficient due to decrease of generator voltage when pressure on the accelerator pedal is relieved. The circuit continues from coil 3c to contacts 3a, a normally closed disabling switch 85 and switch GSl to ground. Another circuit is also established: wire 82, resistance 83, switch AS, wire 86, coil |c of a relay IR, contacts 3a, switch 85, switch GSI. When coil ic is energized normally open contacts la and Ib close and normally closed contacts Id open. The closing of contacts la provides a short circuit around switch AS so that energization of coil lc is maintained although switch AS is opened by depression of the accelerator pedal to increase engine power and vehicle speed. The opening of contacts ld at this time is necessary to prevent disabling of the ignition apparatus. When contacts lb close, the coils 1| and 12 of solenoid Si receive current through the following circuit: wire 82, Wire di?, contacts lb, wire 9i, coils 1| and 12 to ground. The armature 14 of solenoid Sl then moves to the left to eiect the engagement of clutch members 5d and 55, in order to eiect the change of transmission from low to medium. Left movement of the armature 14 is accompanied by a left movement of nut 18 which engages a blade 93 carrying one of a pair of contacts 94 which are in series with the coil 12. Therefore, when the armature 14 is fully attracted coil 12 is open circuited and the armature held in this fully attracted position by coil 1| alone. Coil 12 has fewer turns of coarse wire and coil 1| more turns of finer wire. Therefore, the current consumingv coil 12 is open circuited and current is conserved. Left movement of rod produced by left movement of armature 14 releasespressure on the spring blade |30 carrying a contact adapted to engage a contact |02. Therefore contacts and H32 are closed while the transmission is in medium.

As vehicle speed is increased by increasing engine power while the transmission is in medium status, a speed responsive or governor switch GSZ causes its movable contact H0 connected with a terminal IH to move from a contact H2, which it normally engages, into engagement with a contact H3. Then the following circuit is established: wire 82, resistance H, terminal switch HB at H8', contact H3, coil 2c of a relay 2R to ground. When coil 2c is energized normally closed contacts 2d open and normally open contacts 2b close. The functions of contacts 2d and 2b and relay 2R are identical with the function ofV contacts id and il; of relay IR. The opening of contacts 2d prevents rendering the ignition inoperative unt-il the proper time and the closing of contacts 2b causes solenoid S2 to operate in the manner of operation of Solenoid SL Therefore, to change the transmission from medium to high aiter governor' switch GS2 closes at higher vehicle speed, release of the accelerator pedal will cause a shifting of blocker 36 whereupon the solenoid S2 then having been energized will shift the sun gear locking pawl 25 into engagement with the sun gear locking disc 25. The transr mission is now in high.

When it is desired to shift, from high to intermediate the driver presses the switch DS into closed position to establish a short circuit of coil 2c, said short circuit including switch DS and a switch H5 which is normally closed. The function of switch H5 will be described later. When coil 2c is short circuited, contacts 2o'. return to closed position and contacts 2b are open. The hold-in coil 13 oi solenoid S2 is deenergized and spring 11 attempts to retract the pawl 25` In order that it may do. so, it is necessary to relieve engine torque and this is done by rendering the ignition temporarily inoperative. The ignition system of the engine is represented diagrammatically by wire Irs; connected with wire 82, ignition switch I21I closed when the ignition is operating, ignition coil primary winding |22 and ignition circuit breaker or timer |23 connected to ground. The ignition is rendered inoperative by short circuiting the timer |23. This short circuit,

indicated by small xs, includes wires |213, |25, contacts 2d, wire |26, contacts and |92 o solenoid S2 (closed when rod 2E is down), blade |60, wire |27, terminal switch H5, switch DS to ground. The ignition being inoperative, the engine becomes inoperative and pressure between the disc 24 and the pawl 25 is relieved. Then thespring of solenoid S2 is able to retract the pawl 25 by upward movement of rodV 2S whflhmear the end of its upward movement, separates contacts and It thereby opening the short circuit of the timer |23 so that the ignition is again operative.

Thev transmission having been shifted from high to medium, the driver can release pressure on the switch DS and a spring opens it. Vehicle speed having been reduced by change in trans.- mission from high tomedium, governor switch GS2 moves. its Contact |||l away from Contact ||3 into engagement with Contact 2. driver wishes to return the transmission to high, he depresses the accelerator pedal in order to increasevehicle speed so that the governor switch GSZ will ,move contact IIB againV into engagement with contact Ii@ and solenoid SZ-Willfunction as stated. If the driver wishes to. ShiftA from intermediate to low, he releases pressure on the accelerator pedal to allow the engine power to decrease and vehicle speed will decrease. below that which will keep the governor switch open. The opening of switch GSI opens the cir,- euitcoil |c of relay IR. Therefore, contacts I o'i;V will close and contacts ib and la will open and coil 'I3 of solenoid Si open circuited and .Springy 1T will attempt to move rod $5 toward the right and; lever-B clockwise. To be sure that: this cperation takes place against the force of friction between the teeth of clutch members 5,4, and 5 5, the engine torquey is temporarily relieved by momentarily shorting the ignition timer through the following circuit: wire IM, wire |36, contacts Id then closed, contacts ||3| and |32 (closed when rod 65 is in Clutch engaging position) blade I-0|l, wire |36, wire |21 and terminal ||I, switch I! 5 and switch DS then closed.

Fig. 3 shows a form of; speed responsive switch GSI or GSZ. A gea-r ldE which is driven by the vehicle and is supported by a fixed bearing |5I, carries lugs |52 supporting pins |53 on which weighted levers |54 Vare supported'. Levers |54 are connected with a grooved collar |55 having rods |56 and |57 extending therefrom. ,Rod |58 is received by a. central hole in gear |50. Rod |57 extends through a bushing |58 threaded into a fixed plate |5 and secured in adjusted position. by a nut IE5. The adjustment of bushing |58 determines the compression of'a governor control spring |6| surrounding rod |51 and retained by a seat liti. provided by collar |55k and. by a seat |53v which a thrust bearing |64 spaces from bushing |58- The non-conducting upper end of the rodl |5 is engageable with a lever` |65 pivotally supported at by a post |68 supported. by plate |59 and insulated therefrom. A spring |61 connecting plate |53 with lever |65 urges thev latter 6 counterclockwise. lever |65 receives one end of a U-shaped spring |11) whose other end is received by blade IIB (of switch GSE) which the spring Ii'il urges left into a iulcrum notch |`|2 of a post lit, supported by plate |59 and` insulated therefrom. Normally collar |55 rests on gear itil and spring lli) urges blade il@ counterclockwise so that a contact I'il carried thereby engages the Contact` H2. When vehicle speedy attains a certain value, the left end 0f lever |55 will be above the right end of blade IIB andA spring iii! will cause rapid clockwise movement of blade |||v to disconnect it from contact H2 and to connect it with contact H3.

Similarly when vehicle speed falls to a certain value, and the left end4 of lever it drops below the right end of' blade i@ then in the last mentioned position, spring llc will cause the blade li@ to move quickly counterclockwise to separate it from cont-act :rf and to cause it to engage contact i2.

Governor switch GS| would have a lower contact corresponding to contact ||3 of Fig. 3 and an upper stop corresponding to part |2 of Fig. 3.

The switch shown in Fig. 3 is merely an example o suitable construction of the switches GSi and GSE.

Whenever there is a change in transmission status from high to` medium or from medium to low effected in consequence of closing switch DS, a condition of free wheeling is introduced by reason ci overrunning clutches which include the rollers |52A and 5|. The function of switch |55 is to open the circuit of switch DS, so that inadvertent closing of switch DS' will not be effective to introduce a free wheeling condition when it is desirable to use the engine as a brake as well as the vehicle brakes to stop the vehicle or to assist the vehicle brakes when passing down a steep grade. Switch H5 can be coordinated with the brake applying mechanism so that it will open when brakes are applied or it can be manually opened independent of brake application so that the engine can be used as a brake regardless of vehicle brake application.

In order to show how the circuit of the downswitch DS can be interrupted manually and automatically, reference is made to Fig. 4 which shows, in series with terminal ||I and switch DS., two pairs of normally closed contacts II5a and |I5b. Contacts ||5a are part of a relay ||R whose coil 4c, when energized, separates them. Coil c is in parallel with a stop light |80 which burns when a stop light switch closes in response to application of brakes. A conventional hydraulic brake systemV shown diagrammatically in Fig. 4 includes a brake drum i352 engageable by brake shoes |813 connected with pistons |84 in a cylinder |85 which a pipe mea connects with a cylinder ||l| in which a piston itl slides. Hydraulic fluid in a reservoir |33 can pass into cylinder |535 through ducts |33y and |90. The left end of piston |824 hasv holes |S| leading 'to the back of a softv rubber cup |92 which a piston return spring |93 urges against the left end of piston Ml?. Rod iSd and link |95 connect piston |31 with a brake lever |56 pivoted at |91 and providing a pedal 59S. A spring ie@ urges the lever |96 clockwise. When the pedal |98 is pushed down,` piston lili moves left to force fluid into the brake cylinder |85A to cause separation of the pistons |84. and engagement of shoesl |83 with drum |82 attached to a vehicle wheel. At the same time a diaphragm Eile is caused to flex downwardly against the action of a spring 29| The free end portion |59 of" and cause a contact support 202 to move a switch contact 203 into engagement with contacts 204 and 205 of switch |8I, thus connecting the wire 82 (connecting battery 83 with generator 80, Fig. 1) with the lamp |80 and the relay coil 4c. Contacts |5a are separated so that no down shift or change from higher to lower ratio can take place although switch DS might be closed. When the pedal |98 is released and is returned oy spring |99 to normal position, spring |03 pushes the piston |87 right and nuid pressure is relieved on the pistons |84 which shoe retracting springs urge together and force fluid from the cylinder |85 through pipe |85a to cylinder 86. If pedal |98 is released quickly, the left end of cylinder |86 can receive fluid passing from reservoir |88 through duct |90 and ducts |9| and around the rubber cup |92. Therefore the return of piston |81 is not retarded by return flow through pipe |8512; and :duid pressure falls immediately following release of pedal |98 and switch |8| opens and coil 4c is deenergized and contacts |i5a close by virtue of the action of a spring blade 206 which supports one of them.

The switch contacts H51) are controlled by a lever 2|0 supported by a steering column 2H which supports a steering wheel 2|2. Lever 2|@ is connected with a shaft 2|3 connected with a cam 2 I4 which engages a blade 2|5 carrying the lower one of the contacts H51). Normally lever 2|0 is in the oli-hill position indicated by oi marked on the steering column. When it is desirable to use the engine as a brake on going down a steep grade regardless of use of the vehicle brakes, the driver moves the lever 2 l0 clockwise to hill position, thereby causing the cam 2 4 to release the blade 2 5 which is biased downwardly, for separation of contacts H511, thereby nullifying the effect of the closing of down-switch DS, although the vehicle brakes may not be applied and contacts ||5a may remain in engagement.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms i might be adopted.

1. A system of control for a variable speed transmission for an automotive Vehicle and comprising a member movable in one direction from normal position to effect a decrease in the ratio of engine speed to vehicle axle speed and in the opposite direction to increase the ratio, a solenoid having an armature connected with said member and having windings, energization of which causes movement of the member in the l nrst mentioned direction, a spring opposing movement of the armature and operable to return the member to normal position when the solenoid windings are deenergized, a current source, a

relay having normally open contacts for con- 1f necting, when closed, the solenoid windings with a current source, a relay magnet coil, the energization of which efects closing of the relay contacts, a circuit for connecting the relay magnet coil with a current source and including a switch which closes upon the attainment of a certain vehicle speed and, in series therewith, a switch which is closed by release of the accelerator pedal of the vehicle, a circuit in parallel with the relay coil and its control switches and including a manually operated, normally open down-shift switch, the closing of which short circuits the relay coil whereby the solenoid is ineffective to oppose the return spring, and

y means for momentarily rendering the engine inoperative in order to facilitate action of the return spring to move said member to normal posl tion, said means comprising a short circuit paralleling a portion of the ignition apparatus and including, in series, a switch which is closed when the member moves in the rst mentioned direction, a second pair of relay contacts which close when the relay coil is deenergized and said manually operated switch is closed.

2. A system according to claim l in which the relay has a pair of normally open contacts in parallel with the accelerator pedal controlled switch, the energization of the relay coil causing said contacts to close to by-pass the accelerator pedal controlled switch.

3. A system according to claim 1 in which the control circuit of the relay coil includes a pair of normally open contacts, in which the current source is a generator driven by the vehicle engine, and in which means are provided for effecting closure of said contacts upon the attainment of a certain generator voltage.

4. A system according to claim l in which the control circuit of the relay coil includes a pair of normally open contacts, in which the current source is a generator driven by the vehicle engine, a second relay which includes said contacts and a rst magnet coil connected with the generator whereby the contacts close in response to attainment of a certain generator voltage and which includes a second or holding magnet coil in parallel with the magnet coil of the rst relay and in series with the accelerator pedal controlled switch, the contacts of the second relay and the vehicle speed responsive switch, and in which the rst relay has a pair of normally open contacts in parallel with the accelerator pedal controlled switch, the energization of the coil of the first relay causing the contacts last mentioned to close to by-pass the accelerator pedal controlled switch whereby the circuit of the coil of the first relay and the second coil of the second relay are maintained independently of the accelerator pedal controlled switch.

5. A system according to claim 1 in which there is placed, in series with the normally open, manually closed down-shift switch, a normally closed switch under control by the driver for the purpose of nullifying the effect of inadvertent closing of the down-shift switch.

6. A system according to claim 1 in which there is placed, in series with the normally open, manually closed down-shift switch, a normally closed switch which is caused to open automatically in response to application of brakes for the purpose of nullifying the eiect of inadvertent closing of the down-shift switch.

7. A system of control for a variable speed transmission for an automotive vehicle and comprising rst and second members, each movable from a normal position in a direction to eiect a decrease in the ratio of engine speed to vehicle axle speed and in the opposite direction to increase the ratio, rst and second solenoids associated, respectively, with said members and each including an armature connected with a member and windings which, when energized, cause movement of a member in the rst mentioned direction, springs each for-moving a member in the opposite direction, a current source, rst and second relays having normally open contacts which, when closed, respectively connect windings of the rst and second solenoids with the current source and each having a magnet coil, first and second speed responsive switches operative, upon attainment'of medium and higher Vehicle speeds, respectively, to connect the rst and second relay coils, respectively,

with the current source, said second speed re sponsive switch including a movable contact having a normal contact making position which it occupies at vehicle speeds below the speed at which the second relay coil is connected with the current source, a circuit for shortng the second relay coil and including a normal open, manually closed switch in parallel with the second relay coil and second speed responsive switch and a circuit for shorting the rst relay coil including said manually closed switch and the movable contact of the second speed responsive switch when in normal position.

8. A system according to claim 6 further characterized by means for momentarily rendering the engine ignition inoperative and comprising two circuits each in parallel with a portion of the ignition apparatus and eachv including a pair of normally open switch contacts and a pair of normally closed switch contacts, the pairs of normally open contacts being associated, respectively, with the solenoids and closed in response to magnetic attraction of the solenoid armatures, the pairs of normally closed contacts being parts respectively of the relays and closing when the relay coils are deenergized, and said means including also the normally open, manually closed switch in series with said parallel circuits.

9. A system of control for the transmission of an automotive vehicle comprising a member movable from a normal position in one direction to euect an increase in the ratio oi.' engine .speed 10 to vehicle axle speed and in the opposite direction to reduce the ratio, a solenoid having an armature connected with said member and Windings, the energization of which cause the armature to move the member in the first mentioned direction, a spring opposing said movement of the armature and operable to move the member in the opposite direction when the windings are deenergized, a relay having a coil, means for effecting energization of the coil in response to attainment of a certain vehicle speed, normally open relay contacts closed by energization of the relay coil to cause the solenoid windings to become energized, circuits for shortcircuiting the relay coil and for rendering the Vehicle engine ignition apparatus non-operative and including. in series, a normally closed switch and a normallyv open switch both under control by the driver and means for opening the normally closed switch automatically in response to the application of vehicle brakes.

EDWARD M. CLAYTOR.

REFERENCES CITED The. following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,260,759 Surdy Oct. 28, 1941 2,281,916 Claytor May 5, 1942 2,309,051 Dodge Jan. 19, 1943 2,330,407 Claytor Sept. 28, 1943 *ww-Fr--v-,ffl-.w'r'r 

